from wild birds. In starling blood, for example, 

 the condensed chromatin beneath the nuclear 

 memlnane produces a bumpy contour like that 

 of a mulberry. A narrow condensed nucleus is 

 found also in the common mallard duck. In 

 fact, in this species cells showing the two nuclear 

 types are found in the same smears. For con- 

 venience, one (fig. 4) may be designated as the 

 ovoid, leptochromatic type, and the other as 

 the elongated, pachychromatic type (fig. 5). 

 Breusch (1928) makes the statement (p. 224), 

 ". . . Allgemein kann man weiterhin feststel- 

 len, dasz je junger die orthochromatische Zelle 

 is, um so mehr bezitzt der Kern Blaschenform. 

 . . ." ' However, no data to support this opin- 

 ion are presented. 



Studies are needed on blood physiology and 

 chemistry that would aid in the evaluation of the 



'Translation: In general one may state that the younger the 

 orthochromatic cell is, the more its nucleus has the vesicular 

 form. 



relative merit of each type in relation to the 

 general vigor of the bird. This is a point of 

 more than academic interest. One hypothesis 

 might be that a smaller, more condensed nu- 

 cleus permits the existence of a proportionally 

 larger cytosome and hence a greater content of 

 hemoglobin. Another hypothesis stems from 

 the fact that an oval leptochromatic nucleus is 

 characteristic of immature cells and a conden- 

 sation of chromatin is associated with older cells. 

 The condition in tlie common mallard duck of a 

 mixture of these two types of erythrocytes is 

 some evidence for this hypothesis. Therefore, 

 it is possible that in our Laboratory stock the 

 erythrocytes show a type of nucleus not fully 

 developed because the cells are destroyed before 

 they reach full maturity. 



The existence of amitosis in mature erythro- 

 cytes has been suggested in amphibians (Charip- 

 per and Dawson, 1928). Up to a certain point 



Figures 4-28. — Normal erythrocytes — immature, mature, and aged — found in the circulating blood 



of the hatched chicken. 2,470 X. 



Figures 4-8: Typical mature erythrocytes and variations. 



4 Mature erythrocyte, typical for otir Laboratory 

 stock. Niicleu.s — oval leptochromatic type. 



5 Mature erythrocyte, typical for some other stocks 

 and breeds of chickens, for other domesticated 

 birds, and for wild birds. Nucleus — elongated, 

 pachychromatic type. 



6 Normal erythrocyte with nucleus indented at the 

 end; similar to figure 2, 11. 



7, 8 Mature erythrocytes with two nuclei. The cell in 

 figure 8 shows that the two nuclei may be completely 

 separated. 



Figures 9-23: Immature cells. 



fl An erythroblast, equivalent to that in figure 25.5, 

 which is from the embryo. 



10 A late erythroblast, equivalent to, but smaller than, 

 that in figure 347, which is from the bone marrow. 



11 Early poh'chromatic erythrocyte, equivalent to 

 those in figures 264 and 348, which are from the 

 embryo and the bone marrow, respectively. 



12 Early polychromatic erythrocyte. A few lightly 

 stained spaces characteristic of the erythroblast are 

 still visible in the cytoplasm. 



13 Mid-polychromatic erythrocyte, equivalent to those 

 in figures 350 and 351, which are from the bone 

 marrow. 



14 Mid-polychromatic erythrocyte. 



15 Transition between mid- and late-polychromatic 

 erythrocyte, but included with the latter type. 



16 Late polychromatic erythrocyte. 



17 An atypical late polychromatic erythrocyte. 



18 Late polychromatic erythrocyte. This and figure 

 16 are typical of cells at this stage. 



19 Mature erythrocyte. Nucleus and stroma differen- 

 tiated ahead of changes in cell shape, and thus the 

 round shape is fi.xed. A similar reaction is often 

 found in first generation of erythrocytes in the em- 

 bryo. 



Figures 20-23: Reticulocytes from the circulating blood of 

 1-day-old chicks. 



20 Early stage of reticuloycte; granules are abundant. 



21 Same stage as preceding cell. The color obtained 

 with Wright's counterstain indicates that reticulo- 

 cytes have full complement of hemoglobin. 



22 Partial loss of reticulocyte granules. 



23 Granular material is minimal in amount but is suffi- 

 cient to establish the cell as a reticulocyte. Smaller 

 amounts are confused with precipitated stain. 



Figures 24, 25: Mature erythrocytes. 



24 The type characteristic of Laboratory stock. 



25 A cell approaching senility in Laboratory stock but 

 typical for most other stocks of chickens and for 

 most other birds. Compare with figures 2 and 3. 



Figures 26-28: Aged erythrocytes. 



26 Aged erythrocyte, undergoing p3'knosis. 



27 Aged erythrocyte with vacuolization of the nucleus. 



28 Aged erythrocyte showing continuity between intra- 

 nuclear vacuole and cytosome. 



23 



